The present invention relates to a flame retardant organic resin composition.
Because organic resins with aromatic rings, which are represented by aromatic polycarbonate resins and polyphenylene ether resins, possess superior mechanical strength, electrical characteristics, etc., they are used as engineering plastics in various fields, including OA equipment, electrical and electronic equipment, automobiles, construction and civil engineering. In many cases, these organic resins have been rendered flame retardant for the purpose of fire prevention. One of the methods employed in the past to render such organic resins flame retardant consisted in admixing compounds containing chlorine atoms and bromine atoms to these organic resins. However, organic resin compositions containing compounds of this type had defects such as generating significant amounts of smoke during combustion and producing gases harmful to the human body or gases corrosive to metals and such. For this reason, a considerable number of flame retardant resin compositions have been proposed that do not produce gases harmful to the human body.
In Japanese Unexamined Patent Application Publication No. Hei 08(1996)-176425, a composition was offered that was produced by compounding a silicone resin containing phenyl groups and epoxy groups, which was obtained by the hydrolysis of a phenyl-containing silane and an epoxy-containing silane, with an aromatic polycarbonate resin. However, due to the presence of the epoxy groups, the composition had various problems, such as decreased heat resistance and discoloration. In Japanese Unexamined Patent Application Publication No. Hei 10(1998)-139964, a polycarbonate composition was described that was produced by compounding a high molecular weight silicone resin with a weight average molecular weight in excess of 10,000, which consisted of difunctional siloxane units (D units) and trifunctional siloxane units (T units), with an aromatic polycarbonate resin. However, because the silicone resin used in that composition was a silicone resin of a high molecular weight, it was not easy to prepare. In addition, the flame retardancy of the resultant flame retardant polycarbonate resin composition was insufficient.
In Japanese Unexamined Patent Application Publication No. Hei 11(1999)-140294, a flame retardant polycarbonate resin composition was described that was produced by compounding a phenyl-containing silicone resin comprising difunctional siloxane units (D units) and trifunctional siloxane units (T units) with an aromatic polycarbonate resin. In addition, in Japanese Unexamined Patent Application Publication No. Hei 11(1999)-222559, a flame retardant aromatic polycarbonate resin composition was described that was produced by compounding a phenyl- and alkoxy-containing silicone resin comprising difunctional siloxane units (D units) and trifunctional siloxane units (T units) with an aromatic polycarbonate resin. The flame retardancy of these aromatic polycarbonate resin compositions, however, were not satisfactory for certain intended uses. In Japanese Unexamined Patent Application Publication No. Hei 11(1999)-140329, a flame retardant composition was described that comprised compounding silica powder and a phenyl- and alkyl-containing silicone resin comprising difunctional siloxane units (D units) and trifunctional siloxane units (T units) and including monofunctional siloxane units (M units) with an aromatic polycarbonate resin. However, that aromatic polycarbonate resin composition had various problems, such as the need to admix silica powder in a complicated manufacturing process.
As a result of in-depth investigations directed to solving the above-described problems, the authors of the present invention discovered that the flame retardant property of an aromatic ring-containing organic resin could be considerably improved if a specific branched organopolysiloxane was compounded therewith, thereby arriving at the present invention. It is an object of the present invention to provide an organic resin composition of superior flame retardancy.
A flame retardant organic resin composition comprising
(A) 100 parts by weight of an aromatic ring-containing organic resin and
(B) 0.01-50parts by weight of a branched organopolysiloxane described by average molecular formula
(R13SiO1/2)a(R2SiO3/2)b(SiO4/2)c(R3O1/2)d(HO1/2)e,
where each R1 is independently selected from alkyl groups comprising 1 to 12 carbon atoms and alkenyl groups comprising 2 to 12 carbon atoms; each R2 is independently selected from alkyl groups comprising 1 to 12 carbon atoms, alkenyl groups comprising 2 to 12 carbon atoms, and aryl groups comprising 6 to 12 carbon atoms, where the aryl groups of R2 are at least 30 mol % based on total monovalent hydrocarbon in R1 and R2, R3 represents an alkyl group, subscripts a and b are positive numbers, and subscripts c, d, and e are 0 or positive numbers.
The present invention is a flame retardant organic resin composition comprising
(A) 100 parts by weight of an aromatic ring-containing organic resin and
(B) 0.01-50 parts by weight of a branched organopolysiloxane described by average molecular formula
(R13SiO1/2)a(R2SiO3/2)b(SiO4/2)c(R3O1/2)d(HO1/2)e,
where each R1 is independently selected from alkyl groups comprising 1 to 12 carbon atoms and alkenyl groups comprising 2 to 12 carbon atoms; each R2 is independently selected from alkyl groups comprising 1 to 12 carbon atoms, alkenyl groups comprising 2 to 12 carbon atoms, and aryl groups comprising 6 to 12 carbon atoms, where the aryl groups of R2 are at least 30 mol % based on total monovalent hydrocarbon in R1 and R2, R3 represents an alkyl group, subscripts a and b are positive numbers, and subscripts c, d, and e are 0 or positive numbers.
The aromatic ring-containing organic resin of component (A) used in the present invention is exemplified by aromatic polycarbonate resins and polymer alloys thereof, polyphenylene ether resins and polymer alloys thereof, polyarylate resins, polysulfone resins, aromatic polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, aromatic polyamide resins, polyimide resins, polyamideimide resins, polyphenylene sulfide resins, styrene resins such as polystyrene resins, high-impact polystyrene resins, ABS resins, and AS resins, and other thermoplastic resins; Novolac-series epoxy resins, biphenyl-series epoxy resins, and other epoxy resins; phenolic resins, and other thermosetting resins. Preferable among these resins are aromatic polycarbonate resins and polymer alloys thereof.
The branched organopolysiloxane of component (B) used in the present invention is a component that constitutes a characteristic feature of the present invention and fulfills the function of imparting flame retardancy to component (A). Component (B) is represented by the average molecular formula
(R13SiO1/2)a(R2SiO3/2)b(SiO4/2)c(R3O1/2)d(HO1/2)e,
where each R1 is independently selected from alkyl groups comprising 1 to 12 carbon atoms and alkenyl groups comprising 2 to 12 carbon atoms; each R2 is independently selected from alkyl groups comprising 1 to 12 carbon atoms, alkenyl groups comprising 2 to 12 carbon atoms, and aryl groups comprising 6 to 12 carbon atoms, where the aryl groups of R2 are at least 30 mol % based on total monovalent hydrocarbon in R1 and R2, R3 represents an alkyl group, subscripts a and b are positive numbers, and subscripts c, d, and e are 0 or positive numbers.
In the formula above for R1 and R2, the alkyl groups comprising 1 to 12 carbon atoms are exemplified by methyl, ethyl, n-propyl, isopropyl, butyl, and hexyl, with methyl, ethyl, and isopropyl being the most preferable. The alkenyl groups comprising 2 to 12 carbon atoms are exemplified by vinyl and butenyl. The aryl groups comprising 6 to 12 carbon atoms in R2 are exemplified by phenyl, naphthyl, and tolyl, with phenyl being the most preferable among them. The alkyl groups of R3 are exemplified by methyl, ethyl, propyl, and butyl, and groups represented by the above-mentioned formula R3O, in other words alkoxy groups, are exemplified by methoxy, ethoxy, n-propyloxy, isopropoxy, and butoxy.
In component (B), the content of aryl groups in R2 based on total monovalent hydrocarbon in R1 and R2 must be at least 30 mol %, preferably at least 40 mol %, even more preferably at least 50 mol %, and most preferably at least 60 mol %.
The content of groups represented by the formula R3O, in other words, alkoxy groups, in component (B) can be defined as d/(a+b+c) using subscripts in the average molecular formula of component (B) such that preferably d/(a+b+c) is less than or equal to 0.2 and more preferably less than or equal to 0.1. The content of hydroxyl groups in component (B) is preferably not more than 3 wt %, and, even more preferably, not more than 2 wt %.
The weight average molecular weight of component (B) is generally from 300 to 50,000 and preferably greater than 2000 and less than or equal to 50,000. This is due to the fact that when the weight average molecular weight exceeds 50,000, various problems arise, such as a decrease in the moldability of the present composition. For purposes of the present composition, the weight average molecular weight is typically determined using gel permeation chromatography (GPC).
Component (B) used in the present invention requires trifunctional siloxane units (T units) represented by formula R2SiO3/2 (where R2 is as described above) and monofunctional siloxane units (M units) represented by formula R13SiO1/2 (where R1 is as described above) in each molecule, but so long as it does not impair the object of the present invention, it may contain tetrafunctional siloxane units (Q units) represented by formula SiO4/2 in addition to the trifunctional siloxane units (T units) and monofunctional siloxane units (M units).
The softening point of component (B) used in the present invention is, preferably, not less than 100xc2x0 C., and even more preferably, not less than 120xc2x0 C. This is due to the fact that when the softening point of component (B) is less than 100xc2x0 C., its dispersibility in component (A) decreases, and kneading it with component (A) becomes difficult.
The proportion, in which component (B) is admixed is 0.01-50 parts by weight, preferably 0.1-30 parts by weight, and more preferably, 0.1-10 parts by weight per 100 parts by weight of component (A). This is due to the fact that when this amount is less than 0.01 parts by weight, there are no appreciable effects in terms of enhancing flame retardancy, and there is a decrease in mechanical strength when component (B) exceeds 50 parts by weight.
The present composition comprises the above-described component (A) and component (B); however, in addition to these components, alkali metal salts of organic acids or organic acid esters or alkaline earth metal salts of organic acids or organic acid esters can be compounded therewith, as component (C), in order to further enhance its flame retardancy. The organic acids forming part of component (C) are exemplified by organic sulfonic acids and organic carboxylic acids, while the organic acid esters are exemplified by organic phosphoric acid esters. The alkali metals are exemplified by sodium, potassium, lithium, and cerium, and the alkaline earth metals are exemplified by magnesium, calcium, strontium, and barium. Among them, it is preferable to use metal salts of organic sulfonic acids, with metal salts of perfluoroalkane sulfonic acids and metal salts of aromatic sulfone sulfonic acids being even more preferable. Sodium perfluorobutanesulfonate, potassium perfluorobutanesulfonate, sodium perfluoromethylbutanesulfonate, potassium perfluoromethylbutanesulfonate, sodium perfluorooctanesulfonate, and potassium perfluorooctanesulfonate are suggested as specific examples of the metal salts of perfluoroalkane sulfonic acids. Sodium salt of diphenylsulfone-3-sulfonic acid, potassium salt of diphenylsulfone-3-sulfonic acid, sodium salt of 4,4-dibromodiphenylsulfone-3-sulfonic acid, potassium salt of 4,4-dibromodiphenylsulfone-3-sulfonic acid, calcium salt of 4-chloro-4-nitrodiphenylsulfone-3-sulfonic acid, disodium salt of diphenylsulfone-3,3-disulfonic acid, and dipotassium salt of diphenylsulfone-3,3-disulfonic acid are suggested as specific examples of metal salts of aromatic sulfone sulfonic acids. The quantity of this component (C) is 0.02-1 wt % per 100 parts by weight of component (A).
The composition of the present invention comprises the above-described component (A) and component (B), or component (A), component (B), and component (C); however, in order to further increase its flame retardancy, a fluorocarbon resin powder can be compounded therewith, as component (D). The fluorocarbon resins, from which such fluorocarbon resin powder is obtained, are exemplified by fluoroethylene resins (polymers of monomers in which one or more fluorine atoms are substituted for the hydrogen atoms of ethylene, with tetrafluoroethylene resin as their representative example), chlorotrifluoroethylene resin, tetrafluoroethylene-hexafluoroethylenepropylene resin, fluorinated vinyl resins, vinylidene fluoride resin, and dichlorodifluoroethylene resin. The shape of these fluorocarbon resin powders is normally spherical, but may also be filament-like. Component (D) can be admixed at 0.01-5 parts by weight per 100 parts by weight of component (A).
Various additives known to be useful for aromatic ring-containing organic resins may be compounded with the present composition so long as this does not impair the purpose of the present invention. Such additives are exemplified by glass fiber, glass beads, glass flakes, carbon black, calcium sulfate, calcium carbonate, calcium silicate, titanium oxide, alumina, silica, asbestos, talc, clay, mica, quartz powder, and other inorganic fillers; various synthetic resins, various elastomers, and other organic resin additives; hindered phenolic antioxidants, phosphorous acid ester-type antioxidants, phosphoric acid ester-type antioxidants, amine-type antioxidants, and other antioxidants; aliphatic carboxylic acid esters, paraffin, polyethylene waxes and other lubricants; various organic or inorganic pigments and colorants; benzotriazole-type UV absorbers, benzophenone-type UV absorbers, and other UV absorbers; hindered amine-type light stabilizers and other light stabilizers; phosphorus-based flame retardants and various other flame retardancy-imparting agents; various mold release agents; and various anti-static agents.
The present composition can be easily prepared by uniformly mixing the above-described component (A) and component (B), or component (A) through component (C), or component (A) through component (D). The equipment used for mixing the above components is exemplified by ribbon blenders, Henschel mixers, Banbury mixers, drum tumblers, single screw extruders, double screw extruders, kneaders, multi-screw extruders, and the like. It is preferable to mix the above-mentioned components at a temperature of 200-350xc2x0 C.
The superior flame retardancy of the present composition as described above makes it suitable for use in various applications where the property is required, such as in electrical household appliances, automobile interiors, housing materials, and in materials used for electrical and electronic components.
Hereinbelow, the present invention is explained by referring to working examples. In the working examples, the word xe2x80x9cpartxe2x80x9d refers to xe2x80x9cparts by weight.xe2x80x9d In addition, in the working examples, flame retardancy was measured using the oxygen index in accordance with JIS K 7201, xe2x80x9cPlasticsxe2x80x94Determination of burning behavior by oxygen index.xe2x80x9d
Also, the branched organopolysiloxanes SNR1, SNR2, SNR3, SNR4, SNR5, SNR6, SNR7, SNR8, SNR9, and SNR10 used in the working examples had the average unit formulas and average molecular formulas indicated in Table 1 and the characteristics indicated in Table 2 shown hereinbelow. In addition, in Table 1, Me represents methyl, Pr represents propyl, Ph represents phenyl, M represents a Me3SiO1/2 unit, D represents a Me2SiO2/2 unit, T represents a MeSiO3/2 unit, TPr represents a C3H7SiO3/2 unit, and TPh represents a PhSiO3/2 unit. The analysis of the molecular structure of the branched organopolysiloxanes was carried out using nuclear magnetic resonance spectra (NMR), and the measurement of their weight average molecular weight was carried out using gel permeation chromatography (GPC). Here, xe2x80x9cweight average molecular weightxe2x80x9d is a value obtained by conversion to a polystyrene standard of known molecular weight. Also, the softening point of the branched organopolysiloxanes was measured using melting point-measuring equipment by determining the temperature at which the white fine powder softened and became transparent under a microscope.